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Biomedical subjects

M Souto

Publications and source records attributed to M Souto.

At least 19 recordsLinked to original sources
PubMed2000

Changes in gastroduodenal 5-hydroxytryptamine-containing cells induced by dehydroleucodine.

In previous work, we demonstrated that dehydroleucodine (DhL), a lactone isolated from Artemisia douglasiana Besser, prevents gastroduodenal damage induced by absolute ethanol (EtOH). The present study examined the effects of DhL - applied alone or before EtOH - on gastroduodenal cells containing 5-hydroxytryptamine (5-HT), to clarify the mechanism of action of the drug. Mice were divided into four groups: (I) control; (II) DhL; (III) EtOH, and (IV) DhL + EtOH. Stomachs and duodena were studied by immunohistochemistry and image analysis. EtOH decreased the immunopositive cell number and the area occupied by these cells. This effect was prevented by DhL. DhL alone did not affect the gastric immunopositive cell number and area. Duodena treated only with DhL exhibited a reduction of immunopositive cell number, but no change in area was observed. We propose that the drug probably inhibits the release of the inflammatory mediator 5-HT from endocrine cells, acting as a 'cell stabilizer' in response to injury.

Animals↗
PubMed2000

Constitutive expression of heat shock proteins hsp25 and hsp70 in the rat oviduct during neonatal development, the oestrous cycle and early pregnancy.

Certain heat shock proteins are regulated by steroid hormones and are associated with oestrogen receptor function in reproductive tissues, indicating that these proteins have a role during implantation, decidualization and placentation. In the present study, the expression of hsp25, hsp70 and oestrogen receptor alpha were examined by immunohistochemistry in oviducts from rats during neonatal development, the oestrous cycle and during early pregnancy. Oestrogen receptor alpha was the first protein observed in the neonatal oviduct, and its expression preceded that of hsp70 and hsp25. Although these heat shock proteins have been associated with the oestrogen receptor, this study showed that during early development of the oviduct, the receptor protein was not associated with the concomitant expression of hsp25 and hsp70. However, these heat shock proteins were expressed when oviductal cells became differentiated. In the adult oviduct, hsp70 was more abundant than hsp25, moreover, there were no significant modifications in expression of hsp25 during the oestrous cycle. In contrast, the expression of hsp70 was significantly higher in epithelial cells during dioestrus, when the maximum amount of oestrogen receptor alpha was also observed. Therefore, the present study shows that hsp70, but not hsp25, is an oviductal protein modulated by the oestrous cycle and that it is a protein marker for specific phases of the oestrous cycle. In addition, hsp70 was more responsive to the hormonal changes in the infundibulum and ampullar regions of the oviduct. During early pregnancy, hsp25 expression was downregulated (unlike in the endometrium), whereas hsp70 was relatively abundant in the oviduct. hsp70 was observed in all functional segments of the oviduct during pregnancy, indicating that in the oviduct, this protein is modulated by oestrogens and progesterone and possibly by other pregnancy-related hormones.

Analysis of Variance↗
PubMed1999

Intraoperative respiratory failure in a patient after treatment with bleomycin: previous and current intraoperative exposure to 50% oxygen.

Patients treated with bleomycin (BLM) are at risk of developing acute respiratory distress syndrome (ARDS) post-operatively, and this has been associated with high intraoperative concentrations of oxygen. We report progressive arterial desaturation noticeable 2 h after the start of a 4-h radical neck dissection for which the anaesthesia included 50% O2 in N2O. The patient had received two courses of bleomycin within the previous 2 months and had undergone an uneventful right hemiglossectomy under shorter but otherwise similar anaesthesia 4 weeks previously. His pulmonary function tests before the second procedure showed a slight depression of diffusing capacity (DLco) to 80% of predicted and minimal airway obstruction consistent with his history of smoking. The pulse oximetric reading during his second procedure reached 75%, but rose to 95% after treatment with methylprednisolone salbutamol and inspired O2 concentrations between 80% and 100%. By the end of the procedure, he satisfied the criteria for ARDS and was transferred to the ICU, where he developed bilateral pneumonia, deteriorated and died of multiple organ failure. This case suggests that the risk of hyperoxic pulmonary damage in patients exposed to bleomycin may increase not only with the degree and duration of hyperoxia in a given exposure, but also with the latent effects of recent previous exposure. Near normality of pulmonary function tests cannot be taken as reassurance, and small changes may have more adverse prognostic significance than in patients who have not been exposed to bleomycin.

Anesthesia, Inhalation↗
PubMed1999

A wavelet-based algorithm for detecting clustered microcalcifications in digital mammograms.

A computerized scheme to detect clustered microcalcifications in digital mammograms has been developed. Detection of individual microcalcifications in regions of interest (ROIs) was also performed. The mammograms were previously classified into fatty and dense, according to their breast tissue. The most appropriate wavelet basis and reconstruction levels were selected. To select the wavelet basis, 40 profiles of microcalcifications were decomposed and reconstructed using different types of wavelet functions and different combinations of wavelet coefficients. The symlets with a basis of length 8 were chosen for fatty tissue. For dense tissue, the Daubechies' wavelets with a four-element basis were employed. Two methods to detect individual microcalcifications were evaluated: (a) two-dimensional wavelet transform, and (b) one-dimensional wavelet transform. The second technique yielded the best results, and was used to detect clustered microcalcifications in the complete mammogram. When detecting individual microcalcifications by using two-dimensional wavelet transform we have obtained, for fatty ROIs, a sensitivity of 71.11% at a false positive rate of 7.13 per image. For dense ROIs the sensitivity was 60.76% and the false positive rate, 7.33. The areas (A1) under the AFROC curves were 0.33+/-0.04 and 0.28+/-0.02, respectively. The one-dimensional wavelet transform method yielded 80.44% of sensitivity and 6.43 false positives per image (A1=0.39+/-0.03) for fatty ROIs, and 62.17% and 5.82 false positives per image (A1=0.37+/-0.02) for dense ROIs. For the detection of clusters of microcalcifications in the entire mammogram, the sensitivity was 80.00% with 0.94 false positives per image (A1=0.77+/-0.09) for fatty mammograms, and 72.85% of sensitivity at a false positive detection rate of 2.21 per image (A1=0.64+/-0.07) for dense mammograms. Globally, a sensitivity of 76.43% at a false positive detection rate of 1.57 per image was obtained.

Algorithms↗
PubMed1998

Computer-aided diagnosis: automatic detection of malignant masses in digitized mammograms.

A computerized method to automatically detect malignant masses on digital mammograms based on bilateral subtraction to identify asymmetries between left and right breast images was developed. After the digitization, in order to align left and right mammograms the breast border and nipple were automatically detected. Images were corrected to avoid differences in brightness due to the recording procedure. Left and right mammograms were subtracted and a threshold was applied to obtain a binary image with the information of suspicious areas. The suspicious regions or asymmetries were delimited by a region growing algorithm. Size and eccentricity tests were used to eliminate false-positive responses and texture features were extracted from suspicious regions to reject normal tissue regions. The scheme, tested in 70 pairs of digital mammograms, achieved a true-positive rate of 71% with an average number of 0.67 false positives per image. Computerized detection was evaluated by using free-response operating characteristic analysis (FROC). An area under the AFROC (A1) of 0.667 was obtained. Our results show that the scheme may be helpful to the radiologists by serving as a second reader in mammographic screening. The low number of false positives indicates that our scheme would not confuse the radiologist by suggesting normal regions as suspicious.

Algorithms↗
PubMed1998

Automatic calculation of total lung capacity from automatically traced lung boundaries in postero-anterior and lateral digital chest radiographs.

Total lung capacity (TLC) is a very important parameter in the study of pulmonary function. In the pulmonary function laboratory, it is normally obtained using plethysmography or helium dilution techniques. Several authors have developed methods of calculating the TLC using postero-anterior (PA) and lateral chest radiographs. These methods have not been often used in clinical practice. In the present work, we have developed and automated computer-based method for the calculation of TLC, by determining the pulmonary contours from digital PA and lateral radiographs of the thorax. The automatic tracing of the pulmonary borders is carried out using: (1) a group of reference lines is determined in each radiograph; (2) a family of rectangular regions of interest (ROIs) defined, which include the pulmonary borders, and in each of them the pulmonary border is identified using edge enhancement and thresholding techniques; (3) removing outlaying points from the preliminary boundary set; and (4) the pulmonary border is corrected and completed by means of interpolation, extrapolation, and arc fitting. The TLC is calculated using a computerized form of the radiographic ellipses method of Barnhard. The pulmonary borders were automatically traced in a total of 65 normal radiographs (65 PA and 65 lateral views of the same patients). Three radiologists carried out a subjective evaluation of the automatic tracing of the pulmonary borders, with a finding of no error or only one minor error in 67.7% of the PA evaluations, and in 75.9% of the laterals. Comparing the automatically traced borders with borders traced manually by an expert radiologists, we obtained a precision of 0.990 +/- 0.001 for the PA view, and 0.985 +/- 0.002 for the lateral. The values of TLC obtained by the automatic calculation described here showed a high correlation (r = 0.98) with those obtained by applying the manual Barnhard method.

Adolescent↗
PubMed1997

Computerized automatic system to obtain inspiration/expiration chest roentgenograms without patient collaboration.

We have developed a computerized automatic X-ray image acquisition system. It consists of conventional pressure and flow transducers connected to a commercial data acquisition card installed in a PC/AT, the card output being connected through a relay to a conventional X-ray system. Signal processing, that has been applied for automatic detection of inspiration and expiration in respiratory signals, allows the X-ray equipment activation at a given moment of the respiratory cycle. Radiographs are thus obtained either in inspiration or expiration at tidal volume on anaestesized experimental animals. The system has also been tested on non-collaborating patients.

Animals↗
PubMed1997

Real and simulated clustered microcalcifications in digital mammograms. ROC study of observer performance.

We have developed a model to simulate clustered microcalcifications on digital mammograms. Wavelet transform techniques were used to detect real clustered microcalcifications. A feature analysis process was applied to automatically extract the features describing the individual simulated microcalcifications and clusters from the values of the real clustered microcalcifications present in the mammogram. Subsequently, a database of simulated and real clustered microcalcifications was created. Clusters of microcalcifications from this database were tested for indistinguishability from real ones. Two radiologists and one physicist were asked to indicate whether the microcalcifications were either real or simulated. The responses of the readers were evaluated with a ROC analysis and the area under the curve was calculated. The average ROC area was 0.54 +/- 0.03, indicating there was no statistical difference between real and simulated clustered microcalcifications. The method allows for the creations of simulated clustered microcalcifications that are virtually indistinguishable from real microcalcifications in digital mammograms and could be used to evaluate different image processing techniques.

Biophysical Phenomena↗
PubMed1996

Automatic detection of breast border and nipple in digital mammograms.

Advances in the area of computerized image analysis applied to mammography may have very important practical applications in automatically detecting asymmetries (masses, architectural distortions, etc.) between the two breasts. We have developed a fully automatic technique to detect the breast border and the nipple, this being a necessary prerequisite for further image analysis. To detect the breast border, an algorithm that computes the gradient of gray levels was applied. To detect the nipple, three algorithms were compared (maximum height of the breast border, maximum gradient, and maximum second derivative of the gray levels across the median-top section of the breast). A combined method was also designed. The algorithms were tested on 156 digitized mammograms. The breast segmentation results were evaluated by two expert radiologists and one physicist. In 89% of the mammograms, the computed border was in close agreement with the radiologist's estimated border. Segmentation results were acceptable to be used in computer-aided diagnostic schemes. The mean distance between the position of the nipple indicated by two radiologists by consensus and the position calculated by the computer was 6 mm.

Algorithms↗
PubMed1996

Immunochemical localization of chromaffin cells during the embryogenic migration.

Adrenal medulla together with the sympathetic nervous system constitute an anatomo functional unit. Both tissues derive from precursor cells which originate from the neural crest and later differentiate during migration into sympathetic neurons or chromaffin cells. Biosynthesis enzymes of catecholamines such as DBH (dopamine beta hydroxylase) and PNMT (phenylethanol amine-N-methyl transferase) as well as the neurotransmitter serotonin , can be detected by immunohistochemical techniques from 15 to 20 prenatal days. Cells migrating along the dorsal aorta could be observed at 15 prenatal days. From day 16 on, three distinct cellular groups could be distinguished according to the intensity of the immunoreactivity: chromaffin, paraganglion and sympathetic ganglion cells. From day 18, chromaffin cells immunostained as DBH' PNMT+ or DBH+ PNMT could be detected differentiating into what would be adrenergic or noradrenergic cells, respectively Progenitor cells migrating from the neural crest to the adrenal cortical blastema reach a micro-environment where glucocorticoids could possibly influence gene expression for PNMT in some of these undifferentiated cells, causing adrenaline synthesis. Serotonin(5HT) immunoreactivity is localized from 17 prenatal days in several groups of the paraganglionic cells where they could be a modulator for chromaffin differentiation.

Adrenal Medulla↗
PubMed1995

Computer-assisted diagnosis: the classification of mammographic breast parenchymal patterns.

We have developed a method for the quantification of breast texture by using different algorithms to classify mammograms into the four patterns described by Wolfe (N1, P1, P2 and Dy). The computerized scheme employs craniocaudal views of conventional screen-film mammograms, which are digitized by a laser scanner. We used discriminant analysis to select among different feature-extraction techniques, including Fourier transform, local-contrast analysis, and grey-level distribution and quantification. The method has been evaluated on 117 clinical mammograms previously classified by five radiologists as to mammographic breast parenchymal patterns (MBPPS). The results show differences in agreement among radiologists and computer classification, depending on the Wolfe pattern: excellent for Dy (kappa = 0.77), good for P2 (kappa = 0.52) and N1 (kappa = 0.52) and poor for P1 (kappa = 0.22). Our quantitative texture measure as calculated from digital mammograms may be valuable to radiologists in their assessment of MBPP and therefore useful in establishing an index of risk for developing breast carcinoma.

Algorithms↗
PubMed1995

Digital chest radiography: comparison of unprocessed and processed images in the detection of solitary pulmonary nodules.

PURPOSE: To compare the accuracy with which simulated solitary pulmonary nodules can be identified on digital images of the chest that are unprocessed, processed with adaptive spatial filtering, or processed with global filtering. MATERIALS AND METHODS: Six experienced chest radiologists evaluated 408 test radiographs (136 from each of the three types, half with simulated nodules) and judged whether a nodule was present. Data from the 2,448 observations were evaluated by means of a receiver operating characteristic curve with location methods. RESULTS: Accuracy was significantly better with the adaptive filter technique than with the global technique (P < .05), and it was better with adaptive filtering than with no processing in the detection of pulmonary nodules in the mediastinal-subdiaphragmatic areas (P < .05). No significant difference was found between no processing and global filtering. CONCLUSION: Adaptive filtration is superior to global filtration in the identification of solitary pulmonary nodules and is superior to no processing in nodules projected over the radiopaque areas of the thorax on digital images.

Algorithms↗
PubMed1995

Pulmonary nodules: improved detection with vascular segmentation and extraction with spiral CT. Work in progress.

PURPOSE: To determine whether extraction of pulmonary vessels from computed tomographic (CT) images with automated segmentation improves the detection of pulmonary nodules. MATERIALS AND METHODS: Simulated nodules were superimposed on normal spiral CT images. Eight patients referred for CT assessment of pulmonary nodules were selected for clinical evaluation. Vessels were extracted from both the simulation and clinical study with a three dimensional seeded region-growing algorithm. Three experienced radiologists were asked to locate the nodules and assign a level of confidence to their findings. Sensitivity and proportion of false-positive results per case (FPC) were calculated. Observer performance was evaluated by alternate free-response receiver operating characteristic analysis. RESULTS: Extraction of vascular structures from CT scans improved sensitivity from 63% to 84% in the simulation study and from 58% to 78% in the clinical study. The proportion of FPC decreased from 52% to 24% and from 55% to 12%, respectively. Radiologists performed consistently better with the segmented images than with the original images in both the simulation (P = .006) and the clinical (P = .0013) study. CONCLUSION: Automated vessel subtraction and extraction improves detection of pulmonary nodules.

Adult↗
PubMed1994

Caries inhibition of glass ionomers.

The purpose of this study was to evaluate caries inhibition, comparing a new light-cured glass ionomer liner (Photac-Bond) to the chemically-cured Ketac-Bond, using a non-fluoride releasing linear (Pertac Universal Bond) as the control. Two standardized Class V preparations were placed in 30 permanent molars, the gingival margin placed below the cementoenamel junction. Equal numbers of preparations were restored with liners of Photac-Bond, Ketac-Bond and Pertac Universal Bond, according to the manufacturer's instructions. All teeth were subjected to an artificial caries challenge (pH 4.2) for 5 days, the teeth were sectioned, photographed under polarized light microscopy, and demineralized areas adjacent to the restoration margins were quantitated. Results demonstrated the mean (+/- S.D.) area (micron 2) demineralization 100 microns from the restoration gingival margin to be: Ketac-Bond 12.2 x 10(3) +/- 6.7 x 10(3); Photac-Bond 9.7 x 10(3) +/- 3.6 x 10(3); Pertac Universal Bond 22.3 x 10(3) +/- 8.2 x 10(3). Duncan's multiple range test indicated there was no statistically significant difference in demineralization inhibition comparing Ketac-Bond and Photac-Bond, yet both of these glass ionomer preparations demonstrated significantly less demineralization than the non-fluoride releasing Pertac Universal Bond control linear (P < 0.05).

Analysis of Variance↗
PubMed1993

Scatter in computed radiography.

The effects of scatter radiation on images obtained with storage phosphor computed radiography (CR) were evaluated. The scatter degradation factor was extended to account separately for forward scatter and backscatter. Values for the ratios of forward scatter to primary radiation (sf/p) and backscatter to primary radiation (sb/p) were measured for various x-ray tube potentials, phantom thicknesses, and field sizes for CR imaging plates (IPs). Similar measurements were made for a common screen-film system. The sb/p values for the IPs were 0.05-3.80. Standard CR cassettes do not have lead foil behind the IP to control backscatter; the results of this study indicate that such control is needed. The sf/p values were 40%-70% higher in IPs (50%-120% higher when backscatter was included) than those in the conventional screen-film system. This difference is attributed to the differences in the K-absorption edges of barium and gadolinium and the fact that scatter has lower effective energy than the primary beam as they exit the patient.

Diagnosis, Computer-Assisted↗
PubMed1992

Enhancement of chest images by automatic adaptive spatial filtering.

Postprocessing of the image data is an exciting capability of digital radiography that may improve diagnostic performance. We present a new algorithm that selectively enhances edges and contrast in both lungs and mediastinum while minimally amplifying noise in chest images. Using different size kernels, two smoothed images are generated from the original chest image. The two regions of interest (lungs and mediastinum) are identified based on the distribution of pixel values in the image. A modified nonlinear unsharp mask subtraction technique is then applied. The resulting image has enhanced high- and middle-frequency information in the mediastinum without distorting lung parenchyma or significantly enhancing noise. We consider that the technique employed in this study could be suitable for routine use although its true effectiveness in improving diagnostic accuracy awaits observer-performance evaluation that is currently under way.

Adult↗
PubMed1990

Adrenal cytochrome-c-oxidase and P-450 in male adult rats: effects of testosterone, castration and dexamethasone.

The enzymes cytochrome-c-oxidase and P-450 were measured in adrenal cortex of male adult rats, under four experimental conditions: G1, controls; G2, orchidectomized; G3, orchidectomized and treated with testosterone and G4, orchidectomized and treated with testosterone plus dexamethasone. No differences were observed in cytochrome-c-oxidase between groups G1, G2 and G4. The highest activity was found in G3, which differs significantly from the rest of the groups. No differences were observed from cytochrome P-450 between G1 and G3 groups, while G2 and G4 differ from the G1 group. These studies support new evidences for an interaction between adrenal cortex and gonads in relation to steroidogenic and respiratory activity.

Adrenal Cortex↗